21078026 has 4 divisors (see below), whose sum is σ = 31617042. Its totient is φ = 10539012.

The previous prime is 21077971. The next prime is 21078053. The reversal of 21078026 is 62087012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20259001 + 819025 = 4501^2 + 905^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21077986 and 21078004.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5269505 + ... + 5269508.

Almost surely, 2^21078026 is an apocalyptic number.

21078026 is a deficient number, since it is larger than the sum of its proper divisors (10539016).

21078026 is a wasteful number, since it uses less digits than its factorization.

21078026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10539015.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 21078026 is about 4591.0811362902. The cubic root of 21078026 is about 276.2336902665.

The spelling of 21078026 in words is "twenty-one million, seventy-eight thousand, twenty-six".